Mesquite Gum Purification for AuNP Synthesis

The mesquite gum purification methodology described by Moreno-Trejo et al. [24 (link)] was employed to obtain purified mesquite gum to synthetize AuNPs. First, the mesquite exudate pearls were carefully chosen and cleaned using established methods; basically, the lighter pearls were selected, while the darker pearls, rich in tannins, were discarded from the further process, and then any little sticks from the mesquite tree and any present dirt were mechanically removed from the lighter pearls [29 (link),30 ]. Subsequently, the cleaned pearls were pulverized using a mortar. The resulting powder was then dissolved in distilled water at room temperature and left to hydrate for 24 h. After the hydration period, the liquid was filtered using a Whatman no. 2 filter paper to remove impurities. The filtered solution was then frozen for 15 h and subsequently lyophilized using a FreeZone freeze dryer (Labconco, Kansas City, MO, USA) for 26 h [28 (link)].